The physicochemical and catalytic properties of Cu-containing crystalline zirconia, obtained via sol–gel synthesis in the presence of Yb+3 ions and polyvinylpyrrolidone, are studied as structural additives. DTG/DSC, TEM, XRD and BET means are used to analyze the crystallization, texture, phase uniformity, surface and porosity of ZrO2 nanopowders. It is shown that increasing the copper content (1.3 and 5 wt % from ZrO2) raises the dehydrogenation activity in the temperature range of 100–400°C and lowers the activation energy of acetaldehyde formation. It is found that the activity of all Cu/t-ZrO2 catalysts grows under the effects of the reaction medium, due to the migration and redispersion of copper.

- Oxidation of Phenol and Chlorophenols on Platinized Titanium Anodes in an Acidic Medium

A comparative study of oxidation of phenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol on Pt/Ti and Ce,Pt/Ti electrocatalysts is performed via cyclic voltammetry. It is shown that the surface morphology and roughness of the anode do not change after modification with cerium. The formal kinetic orders of electrooxidation of all compounds are found to be less than one. It is shown that the β temperature coefficients of the rate of oxidation of chlorophenols grow by 10 to 50% when the Ce,Pt/Ti anode is used at a substrate concentration of 1 mM. A tenfold increase in concentration reduces the effect of cerium additive, except for 3-chlorophenol: the latter exhibits a 250% increase in the β value, compared to the Pt/Ti anode.

The catalytic activity of solid electrolytes from the family of complex bismuth vanadates Bi4V2 – 2xM2xO11– δ (BIMEVOX) with V5+ ions partially substituted by 3d metal cations was studied. In the transformations of isobutanol, it was found to depend on the crystal structure (α, β, γ Aurivillius phases), which changes at increased dopant ion contents (хМ). The highly conductive tetragonal γ phase was most active for all BIMEVOX oxides. The activation energy of the dehydrogenation of isobutanol Еincreased linearly with the charge of the Mn+ ion and activation energy of conductivity of the γ phase of BIMEVOX in the series Cu2+ → Fe3+ → Zr4+.

2015.

- REACTIONS OF ISOBUTANOL OVER A NASICON-TYPE NI-CONTAINING CATALYST ACTIVATED BY PLASMA TREATMENTS

Abstract: The effect UV irradiation and silver, copper, and gold ions (M (z+)) supported on titania (anatase) have on the activity of M/TiO2 samples in ethanol conversion at 150-400A degrees C is examined. After UV irradiation, the yields of acetaldehyde and ethylene increase for TiO2 and Ag/TiO2 samples, while the activity of Cu2+/TiO2 decreases. The activation energy of ethanol dehydration declines in the order TiO2 > Au3+ > Cu2+ > Ag+ and correlates linearly with a reduction in the radius of M (z+) in crystal. The number of acidic sites on a M/TiO2 surface titrated via pyridine adsorption grows upon the introduction of M. Unlike Cu2+/TiO2, these sites are not activated after the irradiation of TiO2, Ag+/TiO2, and Au3+/TiO2. According to IR spectral data on adsorbed pyridine, all samples contain Lewis and Bronsted acidic sites.

Abstract: Thermal desorption and reactivity of isopropanol and isobutanol adsorbed on ternary sodiumzirconium orthophosphates M-NZP with ions M2+ = Cu, Ni, Co partially substituting sodium ions is studied. The adsorption sites of isopropanol and its dehydration are shown to differ in terms of kinetic order. Desorption and reaction orders are identical for isobutanol. The activation energy of isopropanol desorption increases for the series Ni (92) > Co (125) > Cu (167) as a linear function of their ionic radii. The activation energy of isobutanol desorption is 40-65 kJ/mol.

Abstract: The catalytic properties of plasma-chemically and thermally treated triple zirconium orthophosphates Na3ZrM(PO4)(3) (M = Zn, Co, Cu) in the transformation of butanol-2 are studied. X-ray photoelectron spectroscopy data indicate that the surface composition of the samples differs from the stoichiometry, especially in the case of M = Cu. The partial reduction of copper ions occurs during plasma-chemical treatment (PCT), while the amount of Cu on the surface of Na3ZrCu(PO4)(3) diminishes. Treatment in an oxygen glow discharge results in a 3-8 times greater yield of the alcohol dehydrogenation product, methyl ethyl ketone. The energy of the alcohol's bonds with the surface is reduced and the dehydration active sites become fully inactivated. In contrast, thermal treatment (TT) results in an increase in the activity of Na3ZrM(PO4)(3) in the dehydration of butanol-2.

Abstract: It is found that alpha, beta, and I" modifications of perovskites Bi4V2 - 2x Cu-2x O11 - delta (BICUVOX) exhibit different activities during catalytic transformations of isobutanol with a selectivity of isobutanal formation 85-100%. Data analysis shows that the site for the alcohol dehydrogenation reaction is the ion pair Cu2+-O2- with the highest activity for a highly conductive gamma-phase. It is shown that the activation energy for aldehyde formation is lower for gamma-phase of the catalyst by a factor of ten than that for its alpha-phase. It is concluded that step-wise Arrhenius dependences without changes in the activation energy for parallel alcohol dehydrogenation and dehydration reactions are related to changes in the conducting properties of the catalyst. Step change in activity was found at temperatures of 310 and 370A degrees and corresponds to an increase of the solid solution electric conductivity.

Abstract: We show that the effect of treatment of supported Mn+-ZrO2 catalysts is different in oxygen and hydrogen plasma. The activating effect of an oxygen plasma is connected with a decrease in the activation energy for dehydrogenation and with a change in the oxidation state of modifier ions. We obtain linear correlations of the catalytic characteristics with the reduction potential and radius of M in different oxidation states.

Abstract: Catalytic and adsorption properties of zirconium triple orthophosphates Na3ZrM(PO4)(3) with M= Zn, Co, Cu in the anionic part of the phosphate are studied. Based on the linear ratios of the catalytic and adsorption characteristics of phosphates with the standard reduction potentials of compensator ions, it is shown that the limiting stage of the dehydration reaction is associated with a reversible change in the charge state of active centers of triple Na-Zr-M-phosphate, which includes compensator ion M that partially replaces zirconium in the anionic part of the phosphate.

Abstract: The dehydrogenation of propanol-2 on sodium-zirconium phosphates (NZP) with the composition Na1 - 2 M Zr-2(PO4)(3) ( = 0.125 and 0.25) in which Na+ ions were replaced by M2+ = Co2+, Ni2+, and Cu2+ ions was studied. The experimental reaction activation energy (a) decreased while transition through the * = 310-340A degrees C temperature; above this temperature, the electrophysical and crystallographic properties of the material changed. These changes were explained by the reversible transfer of Me2+ ions from position M1 to M2 in the NZP lattice. Me2+ centers with different alcohol adsorption forms at < * (one-point) and > * (two-point) participated in the dehydrogenation reaction. For the first form, (a) and the logarithm of the preexponential factor linearly correlated with the ionic radius of M2+. The activity of M-NZP catalysts altered in repeated experiments and in cases when the direction of temperature variations changed.

Abstract: Characteristics of the catalytic activity in the dehydration of butanols of copper-containing sodium-zirconium-phosphates (NZPs), in which Na+ ions substitute for Cu2+ ions are obtained. It was found that in the 100-370 degrees C region, the action energy of the reaction falls upon the transition through temperature T*similar to 300 degrees C, above which the electrophysical and crystallographic properties of phosphates change. The observed dependences are explained by the center (which consists of copper with various positions in the phosphate network at T < T* and T > T*) taking part in the formation of carbonyl compounds. This indicates the presence of a ligand effect, i.e., to structural sensitivity of the dehydration reaction in the case of Cu-NZP catalysts.

Abstract: The reactivity and desorption of butanol-2 adsorbed on Li(3)Fe(2)(PO(4))(3) not subjected and subjected to treatment in a glow discharge hydrogen plasma were studied under flow conditions with a gas chromatographic analysis of products. X-ray photoelectron spectroscopy data showed that the number of phosphate groups on the surface of the phosphate was two times larger than the stoichiometric number and increased after plasma chemical treatment. The strength of butanol-phosphate bonds also increased, and the selectivity of alcohol decomposition with the formation of an olefin (dehydration) and ketone (dehydrogenation) changed. After plasma treatment, dehydrogenation centers were deactivated. The selectivities of alcohol transformations in the adsorbed state and under vapor phase conditions were different. Ketone was formed from adsorbed alcohol because the activation energies of dehydrogenation were equal for the two reaction variants.

Abstract: A shift of the Plasmon absorption spectrum into the long-wave region, which increases with decreasing temperature and increasing duration of low-temperature treatment (LTT), was revealed after LTT at 217-77 K of Au hydrosol with a particle size of 10-11 nm. It was demonstrated that a decrease in the effective concentration of conduction electrons (N (e)) after LTT is accompanied by an alteration in the damping coefficient of plasma resonance oscillations (gamma) and the volume fraction of Au particles (N (V) ). The temperature dependences of gamma and N (V) , just as for silver sol, are stipulated by the tunnel mechanism of the formation of low-temperature defects in the presence of two-dimensionally mobile positively charged aqua complexes X(+)(H(2)O) (n) . A feature of Au sol was revealed: the maximum on dependences of gamma and N (V) on the duration of LTT and the linear gamma-N (e) correlation.

Abstract: The catalytic properties of ternary zirconium phosphates Na(1-2x)Cu(x)Zr(2)(PO(4))(3) in the transformations of butanols were been studied. It was found that the structure of alcohol and the copper content (x = 0, 0.15, 0.25, 0.35) affect the rate and selectivity of dehydration. The activity and selectivity changed as the content of copper that substitutes for sodium ions increased. The general conversion of alcohol and selectivity in dehydration decreased in the series butanol-2 -> isobutanol -> butanol-1, due probably to the change in the apparent activation energy of the reaction, depending on the stability of alcohol binding to the surface.